Donald J. Trump has long used strongman-style threats to prosecute people he vilifies as a campaign tactic, dating back to encouraging his 2016 rallygoers to chant “lock her up” about Hillary Clinton. And during his term as president, he repeatedly pressed the Justice Department to open investigations into his political adversaries.

But as November nears, the former president has escalated his vows to use the raw power of the state to impose and maintain control and to intimidate and punish anyone he perceives as working against him.

After Democrats replaced President Biden with Vice President Kamala Harris as their 2024 nominee — and Mr. Trump’s lead in the polls eroded — Mr. Trump’s targets expanded.

He has been laying the groundwork to claim that there was large-scale voter fraud if he loses, a familiar tactic from his 2016 and 2020 playbooks, but this time coupled with threats of prosecution. Those who may face criminal scrutiny for purported efforts at election fraud, Mr. Trump has declared, will include election workers, a tech giant, political operatives, lawyers and donors working for his opponent.

Over the past month, he has shared a post calling for former President Barack Obama to be subject to “military tribunals” and reposted fake images of well-known Democrats clad in prison garb. He has threatened the Facebook founder Mark Zuckerberg with a life sentence for helping state and local governments fund elections in 2020. He stoked fears of voter intimidation by urging police officers to “watch for the voter fraud” at polling places because some voters may be “afraid of that badge,” and warned that people deemed to have “cheated” in this election “will be prosecuted to the fullest extent of the law.”

“WHEN I WIN, those people that CHEATED will be prosecuted to the fullest extent of the Law, which will include long term prison sentences so that this Depravity of Justice does not happen again,” Mr. Trump wrote on his website Truth Social on Saturday.